title: Seasonal patterns of carbon allocation to respiratory pools in 60-yr-old deciduous (Fagus sylvatica) and evergreen (Picea abies) trees assessed via whole-tree stable carbon isotope labeling.
abstract: • The CO(2) efflux of adult trees is supplied by recent photosynthates and carbon (C) stores. The extent to which these C pools contribute to growth and maintenance respiration (R(G) and R(M), respectively) remains obscure. • Recent photosynthates of adult beech (Fagus sylvatica) and spruce (Picea abies) trees were labeled by exposing whole-tree canopies to (13) C-depleted CO(2). Label was applied three times during the year (in spring, early summer and late summer) and changes in the stable C isotope composition (δ(13) C) of trunk and coarse-root CO(2) efflux were quantified. • Seasonal patterns in C translocation rate (CTR) and fractional contribution of label to CO(2) efflux (F(Label-Max)) were found. CTR was fastest during early summer. In beech, F(Label-Max) was lowest in spring and peaked in trunks during late summer (0.6 ± 0.1, mean ± SE), whereas no trend was observed in coarse roots. No seasonal dynamics in F(Label-Max) were found in spruce. • During spring, the R(G) of beech trunks was largely supplied by C stores. Recent photosynthates supplied growth in early summer and refilled C stores in late summer. In spruce, CO(2) efflux was constantly supplied by a mixture of stored (c. 75%) and recent (c. 25%) C. The hypothesis that R(G) is exclusively supplied by recent photosynthates was rejected for both species.
authors.affiliation: Ecophysiology of Plants, Department of Ecology and Ecosystem Management, Life Science Center Weihenstephan, Technische Universität München, Hans-Carl-von-Carlowitz-Platz 2, 85354 Freising, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Kuptz
authors.affiliation: Pathology of Woody Plants, Department of Ecology and Ecosystem Management, Life Science Center Weihenstephan, Technische Universität München, Hans-Carl-von-Carlowitz-Platz 2, 85354 Freising, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Fleischmann
authors.affiliation: Ecophysiology of Plants, Department of Ecology and Ecosystem Management, Life Science Center Weihenstephan, Technische Universität München, Hans-Carl-von-Carlowitz-Platz 2, 85354 Freising, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Matyssek
authors.affiliation: Ecophysiology of Plants, Department of Ecology and Ecosystem Management, Life Science Center Weihenstephan, Technische Universität München, Hans-Carl-von-Carlowitz-Platz 2, 85354 Freising, Germany.
authors.forename: Thorsten E E
authors.initials: TEE
authors.lastname: Grams
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism*; D002247:Carbon Isotopes; D019069:Cell Respiration; D029964:Fagus / Q000378:metabolism*; D010788:Photosynthesis; D028222:Picea / Q000378:metabolism*; D012621:Seasons
chemical_list: D002247:Carbon Isotopes; D002245:Carbon Dioxide